Engine starting mechanism



New, 20, i955 R M, NARDONE 2,771,067

ENGINE STARTING MECHANISM Filed April 1, 1952 A Traa Mey United StatesPatent ENGINE STARTING MECHANISM Romeo M. Nardone, Teaneck, N. J.,assignor to Joseph J. Mascuch, Maplewood, N. J.

Application April 1, 1952, Serial No. 279,886

8 Claims. (Cl. 123179) movement to the rotating parts of such an engine,to

facilitate starting thereof; the combustion of fuel in the engine beingpromoted by such initial rotation by externally applied torque.

ln engine starting mechanism as commonly employed heretofore, it hasbeen customary to make the engine engaging elements in such form as tobe self-disengaging under the impetus imparted `to the engaged elementof the engine by the first power impulses occurring in the combustionchambers of the engine. For this purpose the inter-engaging elements ofthe starter and engine have commonly been provided with an over-runningor ratchet type of clutch tooth, or jaw, so that the first accelerationof the engine clutch element to a speed beyond that of the starterclutch element causes the starter clutch element to be pushed back tothe disengaged position; the engine then continuing to run under its ownpower, without rotating the starter with it.

offsetting the advantage of self-disengagement, however, is thedisadvantage `that an over-running type of clutch element can notreadily be engaged, with good intercalation of the driving surfaces,under all conditions that may arise. For example, where the startingunit is of the turbo-rotor type, with the rotor being energized byapplication thereto of pressure fluid' generated in a propellant, orrocket type lof pressure generator, the

tendency is toward rapid acceleration of the starter and this in turnmeans that the co-operating clutch elements of the starter yand enginemay fail to engage firmly; or they may do so only after the starterclutch element has attained relatively high speed. Moreover there may bepremature disengagement, due to isolated firing impulses of,insufficient regularity to produce sustained self-operation of theengine. In such instances a second attempt to engage the clutch elementsis called for, but here again the re-engagement may prove even moredifficult to accomplish successfully, because of the manner of formingthe clutch teeth.

A feature `of the present invention is the permanent coupling of thestarter and engine clutch elements, thus eliminating all the hazardsattendant upon use of diseni gaging clutch elements. With such permanentcoupling the starter rotor yassembly continues to rotate after thestarted engine becomes self-operative; and a second feature of theinvention is the incorporation into the starter p of` automatic gearratio changing means, functioning to convert the driving ratio from,say, 6 to l ratio that prevails during starting to a 1 to 1 ratioforvsubsequent operation. Y

A third feature of the invention is a novel fluid-pressure responsivemechanism for controlling the driving ratio between the starter rotorand the engine to be started.

A fourth feature of the invention is a iluid pressure operated enginestarting mechanism involving a turbine rotor, an engine-engagingelement, a reduction gear train connecting the turbine rotor andengine-engaging element, a fluid receiving bellows assembly adapted toapply braking force to one element of said gear train, and means forsupplying iluid under pressure to said rotor and bellows assembly,simultaneously, from a common supply manifold interposed between saidrotor and bellows assembly.

These and other features of the invention will be understo'od uponreference to the following description of the preferred embodiment ofthe invention as illustrated in the accompanying drawings wherein;

Fig. 1 is a central sectional view of the portion of the mechanism lyingon one side of the longitudinal axis; and

Fig. 2 is a sectional view along line 2--2 of Fig. 1.

In these drawings the rotor 5 is shown as secured to the flanged end ofthe central shaft 6, and the engine-engaging element 7 is shown ashaving a rearwardly extending shank 8 that is splined and pinned to thecentral hub 9 of an element having angularly spaced axles l0 carryingthe several planet gears 11 (only one of which is actually shown inFig. 1) which mesh constantly with the sun gear 12 of the planetarysystem; the said gear 12 being formed by cutting gear teeth about theperiphery of central shaft 6, a'long the forward section of the shaft.Planets 11 also mesh constantly with the teeth of orbital gear 13, andare held in assembly therewith by retainer rings 14, 15 insertable incircular grooves cut in the inner periphery of orbital gear 13; therings 14, 15 thus retaining the side plates 16, 17 respectively.

The central shaft and the planet carrier 1t) are supported in thesectional, cylindrical housing 18, 19, 20 by ball bearing assemblies 21,22 retained in place by anges formed 'on the transversely disposedsupporting walls 23 and 24, respectively. Additional ball lbearingassemblies 26, 27 facilitate relative rotation between the shaft 6 andthe planet carrier 10. A fth ball bearing assembly 28 is interposedbetween the flange 29 of wall 24 and the plate 30 which carries the rstseries of turbine blades 31, disposed between the rotor blades 32 andthe circular flange 33 in which are carried the fluid supply nozzles 34,shown best in Fig. 2. These nozzles 34 receive the pressure fluid fromannular manifold 35, to which the fluid is delivered by a conduit (notshown) connecting with the iluid source (a rocket motor or otherpropellant unit, for example). The extending rim 36 of the plate 30supports the third series of turbine blades 37 which receive the fluidafter it passes through the rotor blades 32. The expanded and spentgases are exhausted out of the rear section of the housing, afteremerging from the reaction blades 37.

The automatic ratio changing means above referred to includes two setsof annular brake rings 38, 39 and a speed responsive clutch plate 41shiftable laterally to frictionally engage the plate 17 of the orbitalgear assembly 13-15-17, and thereby cause rotation of the entire geartrain as a single unit, provided there is no simultaneously acting forceto compress the brake rings, one against the other. Such a force doesact, however, during the engine starting phase of. operation; the meansfor producing such force being shown as taking the form of abrake-applying pressure plate 46 having a series of angularly spacedpockets housing bellows assemblies 47 (one only'being visible in Fig. l)whose end plates 48, 49 react upon the pressure plate 46 and thetransverseV wall 24, respectively; the bellows plates 49 having centralVextension that screw into threaded sockets in said wall 24. The Wall 24and the bellows plates 4S, 49 have registering passages serving tointroduce into the interiors of the bellows a part of the supply ofpressure iiuid that is present in the manifold 35. The pressure thusexerted upon the plate 46 is effective to cause application of brakingforce to the orbital gear 13; it being noted that the individual brakerings 38 are secured to the housing by splines 51, while theinter-leaving brake rings 39 are secured, to the orbital gear bysplines. 52.; Springs 40 urge the brake rings back into non-engagingpositions immediately following exhaustion ofthe fluid pressure supply.

To trace through a cycle of operation, upon the introduction of gasesunder pressure into the manifold 35, these gases pass in twodirections-to the left into the bellows units-to engage the brake andthereby lock the orbital. gear 13 to the housing, and to the light, intothe blades of the rotor S, to rotate the shaft 6 at relatively highspeed, and the engine-engaging element 7 at relatively low speed, due tothe speed reducing effect of the planetary system. This rotation of theengine-engaging element is, of course, imparted to the moving parts ofthe engine with which the element 7 is connected, and thereby permitsthe engine to become self-propelling by reason of combustion of its ownfuel in its combustion chambers.

As engine fuel combustion proceeds, the engine speed increases, and thestarter elements 7, 8, 9 and 10 are accelerated correspondingly. Thisincrease in speed produces a proportionate increase in the magnitude ofthe centrifugal force acting upon balls 54 in ball-race SS of planetcarrier 10. As the balls 54 move outward, radially, under the inuence ofthis increasing centrifugal force, the clutch plate 41 is shifted to theright, and the resulting pressure upon orbital gear plate 17 causes theentire orbital gear assembly to begin to rotate in unison with theplanet carrier 10; the brake elements 38, 39 being n0 longer effectiveto prevent such rotation, as the uid pressure in the manifold 35, andbellows 47, has by this time dropped off to a negligibly small value,quite insuicient to hold the brake rings engaged, against thedisengaging pressure of the springs 40. Hence the entire gear train ofthe starter mechanism, including the shaft 6 and rotor 5, becomes asingle rotary unit, synchronized with the;

rotating parts of the engine it started; and because all parts move as asingle, integrated unit, there is no danger of tooth breakage or otherinjury being inflicted by one of such parts upon another.

What I claim is:

l. In an engine starting mechanism, an engine-engaging elementconstantly in driving connection with a engine part, a turbine rotor inaxial alignment with said engineI engaging element, means drivablyconnecting said rotor and element, said connecting means including acarrier, fixed to the said element a planetary gear train comprisingplaet gears rotatably mounted upon the carrier and driven by the rotorand an orbital gear surrounding said planet gears, said orbital gearbeing normally freeto rotate with said planet gears about the commonaxis of rotation of said turbine rotor and engine-engaging element, andmeans responsive to admission of pressure fluid into said mecha- 'nismto both energize said rotor and simultaneously *lock said orbital gearagainst rotation.

2. An engine starting mechanism as dened in claim 1,

wherein said planetary gear train further includes a planet gearcarrier, and centrifugal clutch means for drivably connecting saidplanet gear carrier with said orbital gear.

3. An engine starting mechanism as defined in claim l, wherein said gearlocking means includes a series of brake rings rotatable with Saidorbital gear, .a second series of brake rings secured against rotation,and pressure fluid receiving means for causing said second series ofbrake rings to exert braking force upon said first named series of brakerings.

4. An engine starting mechanism as defined .in claim 1, wherein saidgear locking means includes a series of brake rings rotatable with saidorbital gear, a second series of brake rings secured against rotation,and means including fluid receiving bellows assemblies for causing saidsecond series 0f brake rings to exert braking force upon said firstnamed series of brake rings.

5. In an engine starting mechanismy as defined in claim 4, an annulartiuid supply manifold adjacent said bellows assemblies, and means forestablishing uid ow therel between. v

6. An engine starting mechanism comprising, the combination of anengine-engaging member, a turbine rotor in axial alignment with saidengine-engaging member, means drivably connecting said rotor and member,said connecting means consisting of a carrier fixed to the rotor of aplanetary gear Vtrain comprising planet gears rotatably supported by thecarrier and driven by the rotor, and an orbital gear being normally freeto rotate with said planet gears about the common axis of rotation ofsaid turbine rotor and engine-engaging member, avcentrifugal clutchmeans carried by the planet gear carrier for -drivably connecting saidplanet gear carrier with said orbital gear, and means responsive toadmission of pressure'uid into said mechanism to both energize saidrotor and simultaneously lock said orbital gear against rotation,whereby driving connection of the entire assembly,

through the engine-engaging member, is constantly maintained.

7. An engine starting mechanism comprising, the conivthe rotorcomprising planet gears, and an orbital gear being normally free torotate with said planet gears about the common axis of rotation ofsaidlturbine `rotor and yengine-engaging member, a centrifugal clutchmeans comprising a plurality of balls disposed in a ball-race carried bythe planet gear carrier for -drivably connecting said planet gearcarrier with said orbital gear,` and means responsive to admission -ofpressure fluid into said mechanism to both energize said rotor andsimultaneously lock said orbital gear against rotation, whereby drivingconnection of the entire assembly, through the engine-engaging members,is constantly maintained. d,

8. An engine starting mechanism comprisinglthe com bination as definedin claim l, wherein said gear locking means consists of a series ofbrake rings rotatable with the orbital gear, a second series of brakerings secured against rotation, and pressure fluid receiving means forcausing said second seriesof brake ringsto exert braking force upon saidfirst named series of rings.

References Cited in the file of this patent. i

UNITED STATES PATENTS Great Britain oct.`23,1936

